ISOLATION OF TRICHODERMA-REESEI GENES HIGHLY EXPRESSED ON GLUCOSE-CONTAINING MEDIA - CHARACTERIZATION OF THE TEF1 GENE ENCODING TRANSLATIONELONGATION-FACTOR 1-ALPHA

Genes that are highly expressed on glucose-containing media were isola ted from the filamentous fungus, Trichoderma reesei. A cDNA bank was p repared from glucose-grown fungus, the bank was screened with the same cDNA as a probe, and clones giving the strongest signal were isolated . This resulted in the isolation of previously uncharacterized genes. Five of the genes, representing the most abundant transcripts, corresp onded to 1-3% of the total mRNA population and were clearly more highl y expressed than the phosphoglycerate kinase-encoding gene (pgk1) of T . reesei. Based on sequence homology, one of the genes was identified as tef1, encoding translation elongation factor 1 alpha (TEF). The T. reesei TEF is most related to the Mucor racemosus TEF3, showing an ove rall amino acid similarity of 85%. Interestingly, an exon of only 2 bp seems to be present in T. reesei tef1, comprising the first 2 bp of t he Gly(15) codon.